1. Field of the Invention
The present disclosure relates to a protective relaying system, and more particularly, to a protective relaying system for coupling a server module having duplex communication channels to one of a plurality of protective relaying modules in an electric motor protection relay (EMPR) to allow effective data collection from the plurality of protective relaying modules and a data collection method thereof.
2. Description of the Related Art
In general, a motor protection relay is a device for correctly detecting over-current, phase loss, phase imbalance, reverse phase generated during the startup and operation of a motor by a set operation time to reliably protect the motor.
The motor protection relay converts and outputs a current of the motor through a current transformer, and drives a relay to open a closed contact point when the converted output value is abnormal, thereby blocking power supplied to the motor through the closed contact point to perform motor damage prevention and protection.
In recent years, line control has been computerized while actively carrying out factory automation systems in various industrial fields, and due to this, it is configured with a complex apparatus including a motor protection relay having a plurality of protective relaying modules and a monitoring unit for collecting data therefrom to monitor the line.
FIG. 1 is a view illustrating the configuration of a motor protective relaying system, and FIG. 2 is a view illustrating the configuration of a protective relaying module in FIG. 1.
Referring to FIGS. 1 and 2, a motor protective relaying system in the related art may include a motor protection relay 1, a motor 40 and a remote monitoring unit 30 connected thereto.
The motor protection relay 1 may include a plurality of protective relaying modules 10 and switches 20 connected to the plurality of protective relaying modules 10, respectively, therein. Here, the switches 20 are connected to the motors 40, respectively.
Each of the protective relaying modules 10 is connected to the remote monitoring unit 30 through a communication line 35. Furthermore, the buffer layer 10 performs data communication with the remote monitoring unit 30 through the communication line 35 to transmit data stored therein to the remote monitoring unit 30.
Each of the protective relaying modules 10 may include an MCU 11, a voltage/current sensing unit 12, a memory 13, an input/output port 14, a communication unit 15 and a display unit 16.
The voltage/current sensing unit 12 senses and outputs a current supplied to the motor 40 and a voltage of a power line 50 inputted to the protective relaying module 10. The voltage/current sensing unit 12 senses voltage and current signals from a potential transformer (PT) or current transformer (CT), respectively, and convert and output the sensed voltage and current signals into digital data.
The MCU 11 generates power data from the voltage and current data outputted from the voltage/current sensing unit 12 through various operations. Furthermore, the MCU 11 receives status information from the motor 40 connected to the switch 20 to generate status data. The power data and status data generated by the MCU 11 is stored in the memory 13 as event data.
The MCU 11 compares the event data with reference data stored in the memory 13, and generates a control signal controlling the operation of the switch 20 according to the comparison result. The control signal controls an opening and closing operation of the switch 20 to prevent the damage of the motor 40.
The foregoing MCU 11 receives or outputs various signals through the input/output port 14.
The display unit 16 displays the power data and status data provided from the MCU 11 for a user.
The communication unit 15 is connected to the remote monitoring unit 30 through the communication line 35. The communication unit 15 receives a data request signal from the remote monitoring unit 30, and transmits event data stored in the memory 13 to the remote monitoring unit 30 according to the control of the MCU 11.
The communication unit 15 may have unique ID information, for instance, a station number, and operates in response to calling the relevant station number by the remote monitoring unit 30. Here, the communication unit 15 is connected to the remote monitoring unit 30 through a wired communication scheme via RS-485 cable. Furthermore, the communication unit 15 and remote monitoring unit 30 perform data communication with each other through a half-duplex communication scheme.
FIG. 3 is a flow chart illustrating a data collection operation of a motor protective relaying system in the related art.
Referring to FIGS. 1 through 3, the remote monitoring unit 30 scans a plurality of protective relaying modules 10 in the motor protection relay 1 (S10). In other words, the remote monitoring unit 30 checks a communication connection to the communication unit 15 of the plurality of protective relaying modules 10, respectively, through the communication line 35.
When a communication connection between the remote monitoring unit 30 and the plurality of protective relaying modules 10 is acknowledged, the remote monitoring unit 30 requests data to the plurality of protective relaying modules 10, respectively, for which the connection is confirmed (S20).
Here, the remote monitoring unit 30 sequentially requests data to a plurality of protective relaying modules 10. For instance, when a first protective relaying module 10 through an n-th protective relaying module 10 are provided in the motor protection relay 1 and a communication connection to those modules is confirmed, the remote monitoring unit 30 sequentially requests data to the first protective relaying module 10 through the n-th protective relaying module 10.
The motor protection relay 1 sequentially transmits data from the first protective relaying module 10 to the n-th protective relaying module 10 to the remote monitoring unit 30 (S30).
When data is transmitted from the last protective relaying module 10, the remote monitoring unit 30 releases data communication with the plurality of protective relaying modules 10 and completes data collection (S40).
However, as described above, since a motor protective relaying system in the related art sequentially carries out data communication between the remote monitoring unit 30 and the plurality of protective relaying modules 10 in the motor protection relay 1, a lot of communication time is consumed to allow the remote monitoring unit 30 to complete data collection for the entire protective relaying modules 10.
For instance, if a communication time consumed between one protective relaying module 10 and the remote monitoring unit 30 is “A” seconds (s), then a communication time consumed between the entire plurality of protective relaying modules 10 and the remote monitoring unit 30 becomes “A*N (number of protective relaying modules)”.
In other words, as the number of protective relaying modules 10 within the motor protection relay 1 increases in the motor protective relaying system in the related art, a communication time between the remote monitoring unit 30 and the motor protection relay 1 increases. An increase of such a communication time may reduce the latest effectiveness of the collected data, thereby causing an error in performing the monitoring and control of the motor.